Breath test device for organic components, including alcohol

ABSTRACT

A system for detecting volatile components in a vapor, e.g., alcohol, in the breath of a human subject. A ray of frequencymodulated and collimated light of suitable near infrared wavelength from a source such as a laser or a quartz-halogen lamp, collimated with quartz lenses and appropriate optical interference filters passes through the vapor sample via a path of fixed length and free from light losses except those caused by the volatile components being detected, and strikes a radiant energy detector, setting up an electrical signal which is amplified, electronically processed, filtered, and displayed. The concentration of alcohol or other test vapor affects the amount of energy able to pass through the sample to the detector. The detector determines the energy absorbed by the sample and transmits the result to a readout device, meter, or permanent recording means. The sample can be collected by taking an alveolar (deep lung) sample of the subject&#39;&#39;s breath. The system determines, through Henry&#39;&#39;s law, the blood content of alcohol, ketones, aldehydes, various anesthesias and the like. This system is also applicable to determine combustible gases, for example, in coal mines.



1. A system for determining the amount of an organic compound containing carbon and hydrogen and having a substantial vapor pressure at not over 100* C. and being present in a gaseous mixture substantially free of moisture vapor, including in combination: a. a source of highly stable radiant energy in the near infrared range and of predetermined wavelength, b. means for modulating said energy to a fixed modulation frequency, c. means to collimate and direct a beam of said energy along a desired path, d. a receptacle adapted to contain an amount of vapor to be tested for such amount of compound and having ingress and egress means for said beam of said directed energy, e. means for providing a fixed-length path traveled by said beam between said ingress and egress means, said path in itself imparting no loss in said energy, so that energy loss along said path is due solely to the presence of said compound, f. means to introduce a gaseous mixture into said receptacle, g. a radiation detector in the path of said beam at said egress means to initiate an electrical signal, h. means to amplify and process said electrical signal, i. means for electronically filtering said signal in a narrow band centered at said modulation frequency, and j. means to display the filtered, amplified and processed said signal as an expression of the amount of said compound in said mixture.
 2. The system of claim 1 wherein said radiation detector is a solid state photoconductive radiation transducer.
 3. The system of claim 1 wherein said means to amplify and process said signal comprises analogue-to-digital converter means for converting the amplified signal to digital format, and said means to display said signal displays it in digital format.
 4. The system of claim 1 wherein said fixed path comprises a series of spherical segment mirrors in said receptacle, which refocus each reflection of said beam and thereby prevent light losses.
 5. The system of claim 1 wherein said modulating means comprises a rotating apertured disk and means for rotating said disk at a fixed frequency.
 6. The system of claim 1 having means for maintaining the interior of said receptacle at a fixed predetermined temperature.
 7. The system of claim 1 having means for deactivating operation unless the appropriate operating steps have been properly taken.
 8. The system of claim 1 wherein said gas mixture is human breath.
 9. The system of claim 1 wherein said organic compound is ethanol.
 10. The system of claim 1 wherein said source of energy is a helium neon laser with a wavelength of 3.39 microns.
 11. The system of claim 1 wherein said source of energy is a quartz halogen lamp in combination with infrared filter means for resolving the wavelength regions of interest.
 12. The system of claim 1 wherein there is provided a means to purge said receptacle of said gaseous mixture after testing.
 13. The system of claim 1 wherein said organic compound is acetone.
 14. The system of claim 1 wherein said organic compound is chosen from the group of anesthetics consisting of ether, haldane, chloroform, and cyclohexone.
 15. The system of claim 1 wherein said organic compound is methane and said gaseous mixture is mine gas atmosphere.
 16. The system of claim 1 wherein means is provided to dehydrate said gas mixture before it is introduced into said receptacle.
 17. A system for determining the amount of an organic compound containing carbon and hydrogen and having a substantial vapor pressure at not over 100* C. and being present in a gaseous mixture substantially free of moisture vapor, including in combination: a. a source of radiant energy rich in the near infrared range, b. modulating means for imparting a fixed modulation frequency to said energy, c. means to collimate and direct said energy along a desired path, d. a receptacle adapted to contain an amount of vapor to be tested for such amount of compound and having ingress and egress means for a beam of said directed energy, e. means to introduce a gaseous mixture into said receptacle, f. means for providing a fixed-length path traveled by said beam between said imgress and egress means, said path in itself imparting no loss in said energy, so that energy loss along said path is due solely to the presence of said compound, g. an interference filter at said egress through which said beam passes in a narrow preselected band matching a strong absorption band of said organic compound, h. a radiation detector in the path of said beam after it passes through said interference filter for initiating an electrical signal from said beam, i. means to amplify and process said electrical signal, j. means for filtering said signal electronically in a narrow band centered at said modulation frequency, and k. means to display the amplified, processed and filtered said signal as an expression of the amount of said compound in said mixture.
 18. The system of claim 17 wherein said detector is a solid state photoconductive radiation transducer.
 19. The system of claim 17 wherein said means to amplify and process said signal includes analogue-to-digital converter means for converting the amplified signal to digital format, and wherein said means to display said signal displays it in digital format.
 20. A method for determining the amount of an organic compound containing carbon and hydrogen and having a substantial vapor pressure at not over 100* C. and being present in a gaseous mixture substantially free of moisture vapor, including in combination: a. generating highly stable radiant energy in the near infrared range and of predetermined wavelength, b. modulating said energy to a fixed modulation frequency, c. collimating said energy into a beam and directing said beam along a desired path, d. passing said beam into and out from a receptacle adapted to contain an amount of vapor to be tested for such amount of compound, said beam traveling a fixed-length path in said receptacle, e. preventing loss in said energy in said receptacle except losses due solely to the presence of said compound, f. introducing said gaseous mixture into said receptacle, g. initiating an electrical signal from said beam when it leaves said receptacle, h. amplifying and processing said signal, i. filtering said signal electronically in a narrow band centered at said modulation frequency, and j. displaying the amPlified, filtered, and processed said signal as a fraction of the amount of said compound in said gaseous mixture. 